In recent years, man-made materials excellent in compatibility with biological tissues have been developed in fields of transplantation therapy and the like. Examples of such man-made materials include technology of using a decellularized tissue, which is a support tissue left after removing cells from a biological tissue, as a graft (e.g., Patent Document 1).
The support tissue (collagen and the like) constituting the biological tissue has voids of various sizes inside it. Typically, these voids are filled with biological substances, water and the like. In recent years, it has been attempted that by filling these voids with functional substances such as proteins, polysaccharides, enzymes and synthesized polymers, functionality is given to the biological tissue, which is then utilized as a biological tissue material.
A method of immersing a biological tissue in a liquid containing a functional substance or the like has been known as such an attempt. However, with a method of the immersion, the functional substance is fixed only in a surface layer of the biological tissue, and it is difficult to fill throughout an inside of the biological tissue with a liquid.
Although it is conceivable to fill the biological tissue with the liquid by heat, microwave, ultrasound or the like, these methods may denature and destroy the support tissue that constitutes the biological tissue, and thus a resulting material can be difficult to be used as a biological tissue material.
Thus, it has been desired to develop a method of being capable of filling the biological tissue with a liquid while changes in a structure of the support tissue constituting the biological tissue are inhibited.
[Patent Document 1] Pamphlet of PCT International Publication No. WO2008/111530